Electric control system for photoelectric touch input apparatus

• US 4,904,857 A
• Filed: 12/08/1988
• Issued: 02/27/1990
• Est. Priority Date: 01/13/1986
• Status: Expired due to Fees

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Kishigami, Tomohisa, Ando, Noriyoshi, Mikuni, Hajime
• Primary Examiner(s): Nelms, David C.
• Application Number:
  US07/281,875
• Time in Patent Office: 446 Days
• Field of Search: 250/205, 250/222.1, 250/221, 340/712, 341/31
• US Class Current: 250/205
• CPC Class Codes: H03K 17/14 Modifications for compensating variations of physical values, e.g. of temperature
• CPC Class Codes: H03K 17/943 using a plurality of optical emitters or detectors, e.g. keyboard

Abstract

An electric control system for a photoelectric touch input apparatus including a plurality of light-emitting elements arranged to produce a plurality of light beams in parallel on a common plane and a plurality of photosensitive elements opposed to and aligned with the light-emitting elements to receive the light beams so as to produce a plurality of light-receiving signals at each level of the light beams applied thereto. The control system is arranged to produce a plurality of drive signals respectively representative of a control valve for adjustment of each quantity of light of the light-emitting elements, to apply the drive signals to the light-emitting elements in sequence, to determine as to whether or not each level of the light-receiving signals is less than an optimum level, and if so, to adjust the control value in such a manner that each level of the light-receiving signals reaches the optimum level, and if not, to maintain the control value, to adjust each level of the drive signals in accordance with the control value, and to produce a switchover signal indicative of the position of an object such as an operator'"'"'s finger when it interrupts one of the light beams. In this manner, relative differences in the quantity of light between the light-emitting elements and relative differences in the levels of the light-receiving signals may be compensated for, thereby maintaining the light-receiving signals of the photosensitive elements at an optimum level prior to use of the touch input apparatus.

Claims

1. A photoelectric touch input apparatus adapted to be placed in front of a display device, comprising:

a housing having a frame adapted to be placed in front of a display surface of said display device, said frame defining an opening therein;

a plurality of light-emitting elements mounted on said frame in a row along at least one side of said opening to produce a plurality of light beams in parallel spaced relationship on a common plane;

a plurality of photosensitive elements mounted on said frame in a row along the opposite side of said opening from said plurality of light-emitting elements and aligned with said light-emitting elements to receive the light beams emitted therefrom, said photosensitive elements being arranged to produce a plurality of light-receiving signals in response to the light beams applied thereto from said light-emitting elements;

first means for producing a plurality of drive signals respectively representative of a control value for adjustment of each quantity of light of said light-emitting elements, said first means including means for applying said drive signals to said light-emitting elements in sequence and means for adjusting said control value in such a manner that each level of said light-receiving signals reaches an optimum level, and for memorizing said adjusted control value;

second means for adjusting each level of said drive signals in accordance with said memorized control value only after adjustment of said control value and for maintaining said drive signals at the adjusted level, said second means including means for determining whether or not an object such as an operator'"'"'s finger interrupts one of the light beams, and if so, producing a switchover signal indicative of the position of the object; and

means responsive to said switchover signal to produce a control signal for switching over an indication or picture on the display surface of said display device to another indication or picture defined by said switchover signal.

2. A photoelectric touch input apparatus as recited in claim 1, wherein said first means for producing a plurality of drive signals is arranged to intermittently produce each of said drive signals for a predetermined period of time.

3. A photoelectric touch input apparatus as recited in claim 1, wherein said first means for producing a plurality of drive signals is arranged to produce each of said drive signals representative of a control value in the form of a binary number for adjustment of each quantity of light of said light-emitting elements.

4. A photoelectric touch input apparatus as recited in claim 1, wherein said second means further includes means for permitting adjustment of each level of said drive signals only after adjustment of said control value.

5. A photoelectric touch input apparatus as recited in claim 4, wherein said display device is adapted for use with an automotive vehicle and said first means is activated upon actuation of an ignition switch of said automotive vehicle.

6. A photoelectric touch input apparatus adapted to be placed in front of a display device, comprising:

a housing having a frame adapted to be placed in front of a display surface of said display device, said frame defining an opening therein;

a plurality of light-emitting elements mounted on said frame in a row along at least one side of said opening to produce a plurality of light beams in parallel spaced relationship on a common plane;

a plurality of photosensitive elements mounted on said frame in a row along the opposite side of said opening from said plurality of light-emitting elements and aligned with said light-emitting elements to receive the light beams emitted therefrom, said photosensitive elements being arranged to produce a plurality of light-receiving signals in response to the light beams applied thereto from said light-emitting elements;

first means for producing a plurality of drive signals respectively representative of a control value for adjustment of each quantity of light of said light-emitting elements, said first means including means for applying said drive signals to said light-emitting elements in sequence and means for adjusting said control value in such a manner that each level of said light-receiving signals reaches an optimum level, and for memorizing said adjusted control value; and

second means for adjusting each level of said drive signals in accordance with said memorized control value only after adjustment of said control value and for maintaining said drive signals at the adjusted level, said second means including means for determining whether or not an object such as an operator'"'"'s finger interrupts one of the light beams, and if so, producing a signal indicative of the position of the object.